1. Field of the Invention
The present invention relates to an exhaust system. More particularly, the present invention relates to an exhaust system of a personal watercraft.
2. Description of Related Art
Internal combustion engines are used to power watercraft including watercraft commonly known as personal watercraft. Personal watercraft are generally distinguished from other types of watercraft by a characteristic open stem and a longitudinally extending straddle type seat. In fact, it is said that the operator sits upon a personal watercraft while the operator sits inside other watercraft.
Personal watercraft include a hull which defines an engine compartment. An engine is mounted within the engine compartment and is arranged to drive a water propulsion device. Specifically, the output shaft of the engine is coupled to a water propulsion device of the watercraft, such as a water jet propulsion unit.
The exhaust that is generated by combustion within the engine is routed through an exhaust system to a point external to the watercraft. Generally, the exhaust is discharged into the water in which the watercraft is operating proximate the stem of the watercraft. When the propulsion device is a water jet propulsion unit, the exhaust may be routed into the water that is being expelled from the jet propulsion unit. This results in a cleaner watercraft appearance as well as a decreased noise level associated with the watercraft.
The exhaust systems generally include a first portion that is connected directly to the engine. Exhaust flows from each combustion chamber of the engine through an exhaust discharge port into the first portion. A second portion of the exhaust system is often connected to the first portion and typically leads to the exhaust discharge location. The second portion generally comprises a water box and an exhaust pipe.
The first and second portions of the exhaust system are generally connected together with a coupling sleeve. This coupling sleeve preferably joins the two portions in a leak-resistant manner. The durable life of the coupling sleeve may be significantly shortened as a result of elevated temperatures and excessive vibrations within the exhaust system. Additionally, environmental hazards such as sea salt and the like also may reduce the resiliency and the life expectancy of the coupling sleeve. A combination of these elements may eventually cause the coupling sleeve to split, to crack or to otherwise fail, causing exhaust leaks in the exhaust system.
Moreover, in those instances where the coupling sleeve defines a portion of an exhaust system coolant jacket, a rupture of the coupling sleeve may cause a corresponding coolant jacket rupture. The rupture may result in high temperature coolant flow and possible flooding within the engine compartment or another compartment.
Additionally, the cooling jacket that envelops a substantial portion of the exhaust system is susceptible to plugging. For instance, small stones, sand buildups and plastic bags may become entrained within a portion of the cooling system and occlude a passage. As is known, coolant flowing through the coolant jacket may serve to cool the exhaust system as well as other components. Without adequate cooling, the exhaust system temperature may soar, possibly causing damage to temperature sensitive components within the engine compartment and the like. Additionally, when catalysts are used with the engine to reduce exhaust pollution, the catalyst temperature should be maintained in a desired operative range. Again, an improperly functioning cooling system can deteriorate the performance of such a catalytic device.
Thus, there exists a need for an overheat detection system which will quickly alert an operator to a cooling system malfunction. Additionally, there exists a need for an improved flexible coupling arrangement between the first and second portions of the exhaust system that will reduce vibration translation and heat conduction.
One aspect of the present invention involves a watercraft comprising a hull having an engine compartment. An internal combustion engine is mounted within the engine compartment. The engine comprises at least one cylinder and an exhaust system communicating with the cylinder. The exhaust system comprises a first portion and a second portion. The first portion is connected to the second portion by a flexible coupling member. The first portion has a water jacket defined between a first member and a second member and an exhaust passage defined by the first member. The first member has an opening such that the water jacket and the exhaust passage are in fluid communication. A sensor is mounted at a location that is not upstream of the opening and the sensor is configured to detect a temperature such that the sensor can detect a substantial blockage in the water jacket at substantially any location along the water jacket or another failure of a cooling system associated with the water jacket.
Another aspect of the present invention involves a watercraft comprising a hull having an engine compartment. An internal combustion engine is mounted within the engine compartment. The engine comprises at least one cylinder and an exhaust system communicating with the cylinder. The exhaust system comprises a first portion and a second portion. The first portion is connected to the second portion at least in part by a flexible coupling member. The exhaust system has a water jacket defined between a first member and a second member and an exhaust passage defined by the first member. The first member has an opening such that the water jacket and the exhaust passage are in fluid communication. The opening is positioned downstream of the flexible coupling. The exhaust system further comprises a sensor positioned near the opening. The sensor is configured to detect a temperature such that the sensor can detect a substantial blockage in the water jacket at substantially any location along the water jacket or another failure of a cooling system associated with the water jacket.
A further aspect of the present invention involves a watercraft comprising an engine and an exhaust system coupled to the engine. A cooling system is provided for cooling at least a portion of the exhaust system. The portion of the exhaust system cooled by the cooling system comprises an inner member and an outer member. A water jacket is defined between the inner member and the outer member. The water jacket comprises an inlet and an outlet. The inner member defines an exhaust passage. A sensor system is arranged to detect a substantial blockage in the water jacket. The sensor system comprises a sensor in electrical communication with an overheat prevention unit. The sensor is positioned near the outlet of the water jacket such that the sensor can detect a substantial blockage in the water jacket at substantially any location along the water jacket or another failure of a cooling system associated with the water jacket.
Another aspect of the present invention involves a watercraft comprising an engine and an exhaust system coupled to the engine. The exhaust system comprises a first portion and a second portion. A flexible coupling connects the first portion and the second portion. A cooling system extends along at least one of the first portion and the second portion of the exhaust system. The at least one of the first portion and the second portion of the exhaust system comprises an inner member and an outer member. A water jacket is defined between the inner member and the outer member. The water jacket comprises an inlet and an outlet. The inner member defines an exhaust passage. A sensor system is arranged to detect a substantial blockage in the water jacket. The sensor system comprises a sensor in electrical communication with an overheat prevention unit. The sensor is positioned not upstream of the outlet of the water jacket but is positioned at a location along the exhaust system such that the sensor can detect a substantial blockage in the water jacket at substantially any location along the water jacket or another failure of a cooling system associated with the water jacket.
A further aspect of the present invention involves an exhaust system for an internal combustion engine adapted for marine operation and mounted within a watercraft hull. The exhaust system comprises an exhaust conduit for conducting exhaust gases from the engine and being supported on the engine and a water lock through which the exhaust gases are passed outside of the watercraft. The water lock is supported on the hull. The exhaust conduit and the water lock are spaced from each other. A substantially straight flexible coupling connects the exhaust conduit with the water lock for passing the exhaust gases from the exhaust conduit to the water lock. The flexible coupling allows movement of the exhaust conduit and the water lock relative to each other. A short extension is attached to at least one of the exhaust conduit and the water lock and extends through at least a portion of the flexible coupling such that the flexible coupling is at least partially shielded from direct contact with the exhaust gases.
Another aspect of the present invention involves an exhaust system for an internal combustion engine adapted to a watercraft having a hull and a propulsion device carried by the hull and driven by the engine for propelling the watercraft. The engine is placed on the hull. The exhaust system comprises an exhaust conduit for conducting exhaust gases from the engine and a discharge conduit for discharging the exhaust gases outside of the watercraft. A coupling connects the exhaust conduit with the discharge conduit for running the exhaust gases from the exhaust conduit to the discharge conduit. Means are provided for carrying cooling water to the coupling. A temperature sensor also is provided for sensing temperature of the cooling water near an outlet of the means for carrying cooling water.
An aspect of the present invention also involves an exhaust system for an internal combustion engine adapted for marine use. The exhaust system comprises an exhaust conduit for conducting exhaust gases from the engine and a discharge conduit for discharging the exhaust gases away from the exhaust conduit. A coupling connects the exhaust conduit with the discharge conduit for running the exhaust gases from the exhaust conduit to the discharge conduit. Means are provided for shielding the coupling from the exhaust gases.